Return to index: [Subject] [Thread] [Date] [Author]

RE: ACI 318 paragraph 21.2.5

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Harold,


Thanks for the reply.  Immediately after I posted the original question, I
found the answer in the footnote.  I am still curious about a couple of
issues though.  The project in question is a facility designed to resist
internal blasts and is constructed of substantial reinforced concrete walls
and roof located in a low seismic hazard area.  There is no doubt in my mind
that ASTM A 615 reinforcing, if designed to resist the blast loading, will
be adequate to resist the seismic loadings, however, the reviewer wants to
conform to the code and require A706 material.  Because of the dynamic blast
loading, the design criteria allows for a design yield strength of 81,180
psi (considers an average yield of 66,000 psi with a dynamic increase factor
of 1.23).  The design criteria (COE TM 5-1300) does not address the use of
A706 material. The following questions come to mind.

1. Do you think that the dynamic material properties of A615 and A706
materials are the same?

2. Is there a premium on the material costs?

3.  Why does FEMA 302, which by reference to ACI 318 chapter 21 requires
A706 for special reinforced concrete shear walls, but does not have such a
requirement for special reinforced masonry shear walls?


-----Original Message-----
From: Sprague, Harold O. [mailto:SpragueHO(--nospam--at)bv.com]
Sent: Friday, February 08, 2002 5:27 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: ACI 318 paragraph 21.2.5


Warren,

There were 2 problems with A615 bar that ACI was trying to address.  One was
establishing an upper yield strength limit so that inelastic rotation would
occur at a predicable level.     The second problem was to have a yield
strength greater than the tensile strength to get greater inelastic
rotation.

A706 has established a minimum and a maximum yield strength directly listed
in Table 2.  Table 2 also has a footnote that is almost identical to
21.2.5(b).

Regards,
Harold O. Sprague

> -----Original Message-----
> From:	Foy, Warren [SMTP:Warren.Foy(--nospam--at)mhgrp.com]
> Sent:	Friday, February 08, 2002 12:44 PM
> To:	seaint(--nospam--at)seaint.org
> Subject:	ACI 318 paragraph 21.2.5
>
> Can anyone explain the intent of this paragraphs' requirement that if ASTM
> A615 material is used, "the ratio of the actual ultimate tensile strength
> to
> the actual tensile yield strength is not less than 1.25"?  It seems that
> the
> intent is to establish an upper limit on yield strength similar to the
> requirements of ASTM A706 but I do not see the 1.25 ratio requirements in
> ASTM A706.
>
> Warren S. Foy
> Structural Design Manager
> The Mason & Hanger Group Inc.
>
>
> 300 West Vine Street, Suite 1300
> Lexington, KY   40507-1814
> voice: 859.252.9980
> fax: 859.389.8870
> web: http://www.mhgrp.com
>

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********